Method of forming a cover for a package



y 13, 1935 R. A. FARRELL ETAL A 3,183,800

METHOD OF FORMING A COVER FOR A PACKAGE Original Filed Feb. 26, 1963 2sheetssheet l INVENTORS ROBERT :4. Fflll-LL GEmEGE V. SkouJRdNS/(I BYATTOPfifY y 13, 1955 R. A. FARRELL ETAL 3,183,800

METHOD OF FORMING A COVER FOR A PACKAGE Original Filed Feb. 26, 1963 2Sheets-Sheet 2 INVENTORS RoaegT ,4. FARRELL GEORGE V. JKpwRoNS/{l BYUnited States Patent Ofiice areas Patented May 18, 1965 3,183,800MLETHOD GI FORMING A COVER FOR A PACKAGE Robert A. Farrell, Menasha, andGeorge V. Skowronski, Neenah, Wis., assignors to American Can Company,New York, N.Y., a corporation of New Jersey Original application Feb.26, 1963, Ser. No. 261,566, now Patent No. 3,158,491, dated Nov. 24,1964. Divided and this application Nov. 14, 1963, Ser. No. 323,718

3 Claims. (Cl. 9336) This invention relates to a heat-sealed leakproofpackage. More specifically, the invention relates to a hermeticallysealed package, having an opening means therein, for the packaging ofprepared foods, such as potato salad, sandwich spreads, and frozenfoods. This application is a division of Serial No. 261,566 filedFebruary 26, 1963, now Patent No. 3,158,491, issued Nov. 24, 1964.

In the food merchandising industry it is particularly important to havepackages which are hermetically sealed, have suflicient rigidity ofconstruction for stacking during shipment and can be readily opened. Inaddition, if the packages are to be displayed, it is advantageous tohave a window in the top for easy viewing of the contents withoutdestroying the airtight seal and tamperproofness. Furthermore, it isimportant that the package components be shipped in stacked and nestedcondition to the product packager to save storage space prior to theformation of the completed package.

The package is formed from a rigid receptacle portion, such as a taperedplastic tray, having a bottom and continuous side with an outwardlyextending continuous flange around the entire perimeter at the upperedge thereof and a separate cover portion which is heat-sealed to theupper surface of said flange after the receptacle portion is filled. Thecover portion comprises frangible material, such as paperboard, having aheat-scalable coating, such as polyethylene, on the inner surfacethereof. Lines of weakness in the frangible material define both aremovable panel providing a window and opening means to gain access tothe contents of the package. The polyethylene, in addition to providinga sealing medium, serves to provide a liquid impermeable closure.

The particular objects and advantages of the invention will be madeclear from the following description in connection with the accompanyingdrawings, in which:

FIGURE 1 is a diagrammatic representation of a method for continuouslyconverting suitable materials into blanks for use as cover portions offood packages,

FIGURE 2 is a top view of one of the blanks produced according to ourmethod,

FIGURE 3 is a bottom view of the blank of FIGURE 2,

FIGURE 4 is a perspective of a food package made according to thepresent invention, 1

FIGURE 4A is a partial sectional view taken along line 4A4A of FIGURE 4showing the superposed layers at the perimeter of the package,

FIGURE 5 is a perspective view of the food package having the windowpanel removed,

FIGURE 6 is a perspective view of the food package having the openingmeans partially removed, and

FIGURE 7 is a perspective view of the food package having the openingmeans and window portion removed and the contents exposed. i

Referring more particularly to FIGURE 1, there is shown a continuousmethod for converting a frangible material, i.e., paperboard, and aheat-scalable material, i.e., polyethylene, into composite blanks, suchas the one depicted in FIGURES 2 and 3. Initially, a web of paperboard10 is unwound and the leading edge threaded through the rolls in themanner shown in FIGURE 1. The paperboard is fed through applicator roll11 and back-up roll 12, denoting generically a multi-color press, forprinting the web with any desired indicia. The applicator roll 11transfers the ink from an ink bath 13. After passing through the rolls11 and 12, a pattern of release agent is applied to the unprinted sideof the blank by applicator roll 14 in conjunction with back-up roll 15.The bath 18, from which the release agent is transferred to applicatorroll 14 by means of pick-up roll 17 and transfer roll 16, is shown onthe opposite side of the web from applicator roll 11 to emphasize thefact that the release agent is applied on one side of the web, while theprinting is applied to the other. In the composite blank, shown inFIGURE 3, the area covered by the release agent is indicated by thestippling. Any suitable means, such as gravure cylinder, may be employedfor applying the release agent. A variety of release agents may beemployed, the choice being determined by the heat-seala'ole material tobe applied to the paperboard. For instance, when polyethylene is thematerial to be applied to the web, the following coatings areparticularly desirable since they give high gloss and clarity to thepolyethylene as well as excellent release properties to the paperboard:

(l) A solution of 60% xylene and 40% of a mixture of: 98% DOW PS3polystyrenea low molecular weight polystyrene produced by the DowChemical Company, and 2% Slipeze-a fatty acid amine commercial releaseagent produced by Fine Organics, Inc.

(2) A solution of 86% blended, volatile organic solvents and 14% 1/2Second Butyratea cellulose acetate butyrate produced by Eastman ChemicalCo.

The printed and coated web 10 then passes through a first cuttingstation comprising tensioning rolls 19, 25, eccentric synchronizingrolls 20, 24 for feeding the web to and from the cutting means 22 andtensioning rolls 21 and 23 immediately adjacent the cutting means. Asthe web is advanced through the cutting station, the eccen tricsynchronizing rolls 20, 24 facilitate intermittent starting and stoppingof the web coordinated with the reciprocating action of the cuttingmeans 22. The first cut produces all the cutting and creasing linesimpressed in the blank exclusive of the outer edge, as shown in FIGURES2 and 3. Included in the first cutting and creasing step are partial cutline 46, which extends inward from the printed side only about halfwaythrough the thickness of the paperboard, cut lines 41, angled lines ofweakness 42, score line 45 and cut lines defining cut out areas 54 and55.

The web 16 next passes over idler roll 25 and around drum 28. Anextruder 26 positioned above the nip formed by. idler roll 25 and drum2,8 extrudes a film of polyethylene- 61 onto the traveling web on theside having the release coating thereon. All of the cut lines arecovered and sealed by the extruded coating material. The thickness ofthe extrusion coating, generally between one and two mils, varies withthe material employed and with the degree of strength and, protectionrequired.

I the perimeter of the paperboard.

The composite web then travels over idler roll 29, feed rolls 3t), 31,constant tension roll 32 and idler roll 33 into a second cutting means34 which separates the web into composite blanks A shown in FIGURES 2and 3. As the blanks leave the second cutting means 34, they aretransferred to an endless moving outfeed belt 35 rotating around pulley36 and then removed for packing. The blanks are stacked, boxed andshipped to the product packager for use with receptacle portions to formcompleted packages.

The composite. blank A comprising paperboard and polyethylene is dividedby partial cut line 4%, cut lines 41, angled cut lines 42 and score lineas into edge panel 50, tear strip 51, center panel 52 and pull tab 53. Atearaway element 51a, shown in FIGURES 2 and 4, is defined by partialcut line 40 and the portions of angled cut lines 42 parallel to saidpartial out line 4! Edge 43 of the center panel 52 and cut lines 41define an area 54 in which the paperboard has been removed to facilitateremoval of the center panel 52 for display purposes. Similarly the freeedge of pull tab 53 and cut lines 44 define an area 55 in which thepaperboard has been removed to facilitate grasping of the pull tab 53for removal of the tear strip. As is readily apparent from FIGURE 3, thepolyethylene layer is coextensive with The. food package is formed byfirst filling a receptacle portion such as tapered tray 60 shown inFIGURE 4,

aisasoo with the commodity to be packaged. The receptacle portioncomprises a bottom panel and continuous side walls connected therewith.The upper edges of the side Walls terminate in a continuous outwardlyextending flange portion tia'which is preferably smooth and flat at itsupper surface and preferably extends in a substantially horizontalplane. Trays made from materials, such as high density polyethylene, areparticularly suitable since they provide a rigid construction at aneconomical price and can be heat-sealed readily to a variety ofmaterials, such as 'high or low density polyethylene. 1 After the tray6t) is filled with product 76) (see FIGURES 5-7), the blank A, which isthe cover, is placed on the tray. The

the tear strip 51 is removed causing peeling of the upper surface of thecover. Partial cut line limits the extent of outward peeling so thattear element 51a is uniformly removed down to about one-half thethickness of the paperboard while the remainder of the cover remainsintact.

It is obvious that materials other than those described previously maybe employed. For instance, the receptacle portion may be made ofpolystyrene or polypropylene and the heat-sealable material may be anyof a variety of coated cellophane. The choice of the particularmaterials will be dictated by the properties of each. In order to insurea hermetically sealed package, the heat-sealable material on the covermust readily seal to the receptacle portion. Also the release agentshould not cloud the heat-sealable material so as to detract from theappearance of the Window for display purposes. The opening means willnot function properly unless the degree of adhesion between theheat-scalable material and the frangible material of the cover issufficient to prevent their separation when the tear strip is removed.

If desired, the receptacle portion may be made of coated paperboard andhave a foil lining on the inner surface. Then, after opening, thepackage can be immediately inserted in the oven and the contents bakedin the receptacle portion.

The present invention provides a tamperproof hermetically sealedpackage, which can readily be stacked for shipping purposes. The packageprovides a'window panel which may be removed for display purposes andalso a tear strip which provides ready access to the contents. Since thefrangible cover material never contacts the contents in the completedclosed package, there is no wicking of the product. The receptacle mayin some instances be'used to bake the contents of the package withoutthe necessity of employing a separate vessel. The

outer edge of the outwardly extending flange portion 63a of the tray, asshown in FIGURE 4A, coincides with the outer edge of the blank or cover.The cover is placed with the polyethylene layer 61 in contact with-theflange portion 60a. Heat and pressure are then applied around the entireperimeter of the cover. portion to heat-seal the polyethylene layer 61and the flange portion 6% together. Upon completion of the sealingstep'the contents of the package are hermetically enclosed. Thecompleted package is shown in FIGURE 4.

The center panel 52 can be removed for the displaying of the contents 76by grasping at the edge 43 and pulling upward to detach along lines ofweakness 4-1. Because of the release agent on the inner surface of thecover portion (see the stippled area of FIGURE 3), the center panel 52can easily be removed without disturbing the underlying layer ofpolyethylene (see FIGURE 5); i In addition, the polyethylene exposed hasa high gloss and high degreeof clarity due to the particular releaseagent employed. The completed package having the center,

panel 52 removed is shown in FIGURE 5.

The packageis opened and the contentsexposed by grasping the pull tab SSandlifting and pulling the tear strip 51 back upon itself, as shown inFIGURE 6. The

extruded polyethylene 61 adheres to the underside of the a tear strip51. and is removed along 'with tear strip.

After completely removing the tear strip'5l the contents ofrthe packageare exposed, as shown inFIGURE 7.

The relationship between the thickness of the paperboard and thethickness of the polyethylene is governed bythe need for thepolyethylene to tear before the paperboard breaks or peels'back therebypreventing opening. The

to remainiattached to thetear-away element 51a when use of a preformedplastic tray for the receptacle portion reduces the equipment requiredby the packager for setting up cartons from blanks. In addition toproviding an attractive appearance to the completed package, the

tray. can be reused by the consumer for storage.

It is to be understood that the size and the shape of the package andthe materials from which it is formed may be varied in numerous ways bythose skilled in the art without departing from the spirit of theinvention.

. We claim: 7 V

1; The method of forming a cover to be used with a V receptacle portionto form a leakproof package with an portions betweenthe individualangled cut'lines .42 tend opening means, which method comprises passinga web of frangible material through a first cutting station and imposingin {the web pairs of spaced, substantially parallel, closed lines pf.weakness defining tear strips, coating said Web with a material which isheat-activatable, passing said web through a second cutting station andproducing cover-defining cuts and separating the resulting individualcovers from the remainder of the web.

2. The method of forming a cover to be used with a receptacle portion toform a leakproof package with an opening means, which method comprisespassing a web of paperboard through a first cutting station'and imposingin the web pairs of spaced, substantially parallel, closed lines ofWeakness defining tear strips, extruding polyethylene over an. entireweb. surface, passing said web through a second cutting station andproducing "cover-defining cuts, and continuously separating the reinpredetermined areas; passing the web through a first cutting stationandimposing in the web pairsof spaced,

'subs'tantiallyparallel, closed-lines of weakness defining tear strips,the innermost line of Weakness of each pair surrounding one of saidareas and being essentially coincident with the outer edge thereof;coating the side of the web opposite the release agent bearing side witha material which is heat-activatable; passing said web through a secondcutting station and imposing cover-defining cuts, and continuouslyseparating the resulting individual covers from the remainder of theweb.

References Cited by the Examiner UNITED STATES PATENTS 5 3,004,697 10/61Stone.

3,097,574 7/63 Kuchenbecker 93-36 3,110,434 11/63 Lindaet al.

FOREIGN PATENTS 2/63 Great Britain.

FRANK E. BAILEY, Primary Examiner.

FRANKLIN T. GARRETT, WHITMORE A. WILTZ,

Examiners.

1. THE METHOD OF FORMING A COVER TO BE USED WITH A RECEPTACLE PORTION TOFORM A LEAKPROOF PACKAGE WITH AN OPENING MEANS, WHICH METHOD COMPRISESPASSING A WEB OF FRANGIBLE MATERIAL THROUGH A FIRST CUTTING STATION ANDIMPOSING IN THE WEB PAIRS OF SPACED, SUBSTANTIALLY PARALLEL, CLOSEDLINES OF WEAKNESS DEFINING TEAR STRIPS, COATING SAID WEB WITH A MATERIALWHICH IS HEAT- ACTIVATABLE, PASSING SAID WEB THROUGH A SECOND CUTTINGSTATION AND PRODUCING COVER-DEFINING CUTS AND SEPARATING THE RESULTINGINDIVIDUAL COVERS FROM THE REMAINDER OF THE WEB.